Film threading mechanism for cinematographic apparatus

ABSTRACT

Automatic film threading mechanism for use in motion picture projectors wherein a motor-driven belt can rotate the supply reel in a direction to pay out the convoluted film. The leader of the outermost convolution is intercepted by the tip of a slide reciprocable radially of the supply reel by a transmission including a friction clutch which insures that the tip engages the outermost convolution with a given force irrespective of the diam

United States Patent Riedel I 1451 July 1 l, 1972 [54] FILM THREADINGMECHANISM FOR [56] References Cited CINEMATOGRAPHIC APPARATUS UNITEDSTATES PATENTS Inventor: Wolfgang Riedel, Winnenden, Germany 3,429,5182/1969 McKee ,.352/l58 x v 3,536,276 10/1970 Bundschuh et al..-......242/ I92 [731 Assgnee' 3?: a "2 Gmbu 3,550,881 12/1970 Roman..242/192 e many 3,558,028 1/1971 Bunting ..242/2o9 [22] Filed: Aug. 7,1970 Primary Examiner-George F. Mautz PP -i 62,036 Anomey-Michael S.Striker [30] Foreign Application Priority Data [57] ABSTRACT Automaticfilm threading mechanism for use in motion pic- Aug. l4, l969 Germany..P 19 4] 3l9.5 ture projectors wherein a motopdriven belt can rotatethe supply reel in a direction to pay out the convoluted film. The [52]US. CL... .;...242/l92 leader of the outermost convolution isintercepted by the tip [5 1 Int. Cl ..B65h 17/24 of a slide reciprocableradially of the supply reel by a transmis- [58] Field of Search 242/192, 195, I97, 210, 206. 207 sion including a friction clutch whichinsures that the tip en- B,4C, 11 B, ll C gages the outermostconvolution with a given force irrespective of the diameter of suchconvolution. The slide directs the leader into a film channel whereinthe leader advances into the range of a claw pull-down 9 Claim 3 DrawingFigures PATENTEDJUL 11 1912 3.675874 INVENTOR WolfgongRlEDEL y 2 mm K/Myhis ATTORNEY FILM THREADING MECHANISM FOR CINEMATOGRAPHIC APPARATUSBACKGROUND OF THE INVENTION The present invention relates tocinematographic apparatus, particularly to projectors for motion picturefilm. Still more particularly, the invention relates to improvements inautomatic film threading mechanisms for use in projectors for motionpicture film.

It is already known to provide in an automatic film threading mechanisma drive which moves a belt into engagement with the outermostconvolution of film on a supply reel so that the belt can rotate thereel in a direction to pay out the film, and a pivotable one-armed leverwhich can be moved into engagement with the outermost convolutiondownstream of the point where the film is engaged by the belt wherebythe lever deflects the leader of film into a channel defined by one ormore stationary guides. The thus deflected leader is thereupon engagedby the film transporting mechanism and is transported toward engagementwith the core of the takeup reel. The tip of the lever resembles a wedgeand has a surface which directs the leader into the channel wherein theleader advances past the claw pull-down, past the gate, and on towardthe takeup reel.

A drawback of such film threading mechanisms is that the angularposition of the lever during engagement with the outermost convolutionof film on the supply reel depends on and varies with the diameter ofthe outermost convolution. Thus, if the convoluted film is rather short,the diameter of the outermost convolution is small and the angularposition of the lever is different from the position which the leverassumes when its tip engages the outermost convolution of a long film.Consequently, the lever is not always capable of properly directing theleader into the channel wherein the leader advances toward the clawpull-down. It was found that satisfactory threading of the film isinsured only when the angle between the film directing surface of thelever and the foremost portion of the channel at least approximates acertain value. Consequently, the just described film threadingmechanisms will operate satisfactorily only when the projector is usedwith supply reels each of which contains a supply of convoluted filmhaving a fixed length. Furthermore, the designer of the projector haslittle freedom in selecting the position of the pivot for the lever; thepivot cannot be placed too far awayv SUMMARY OF THE INVENTION An objectof the invention is to provide a cinematographic apparatus, particularlya projector for motion picture film, with a novel and improved automaticfilm threading mechanism whose operation is not dependent on thediameter of the film which is convoluted on the supply reel.

Another object of the invention is to provide a film threading mechanismwhich is simpler, more reliable and more versatile than presently knownfilm threading mechanisms.

A further object of the invention is to provide a film threadingmechanism which need not utilize a film engaging lever.

An additional object of the invention is to provide a film threadingmechanism which can be installed in presently known cinematographicapparatus.

Still another object of the invention is to provide a film threadingmechanism which can control the movements of leaders on large or smallrolls of convoluted motion picture film with the same degree ofaccuracy.

The invention is embodied in a cinematographic apparatus which comprisesa housing, a supply reel rotatably mounted on the housing and supportinga supply of convoluted motion picture film whose leader constitutes thefree end portion of the outermost convolution, and a novel filmthreading mechanism which comprises guide means defining a first pathinto the range of the film advancing element in a customary filmtransporting mechanism), drive means for rotating the reel in adirectionto pay out the film, and deflector means for directing the leader intothe first path. The deflector means comprises a film engaging elementwhich is movable toward and away from the outermost convolution of thefilm along a second path at least a portion of which is straight andpreferably extends at least substantially radially of the reel, anddisplacing means (preferably including a friction clutch) for moving thefilm engaging element along the second path whereby the tip of the filmengaging element deflects the leader into the first path when it engagesthe outermost convolution while the reel rotates in the direction to payout the film.

Since the film engaging element moves along a straight path whichpreferably extends radially of the supply reel, the angle between itsfilm directing surface and the first path remains unchanged irrespectiveof the diameter of outermost convolution of film on the reel. Also, thereciprocable film engaging element requires less room than a lever, andthe designer of the apparatus has more freedom in selecting the positionof the reciprocable element with reference to the spindle for the supplyreel.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved cinematographic apparatus itself, however, both as to itsconstruction and its mode of operation, together with additionalfeatures and advantages thereof, will be best understood upon perusal ofthe following detailed description of certain specific embodiments withreference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary elevationalview of a cinematographic apparatus having a film threading mechanismwhich embodies one form of the invention;

FIG. 2 is an enlarged sectional view as seen in the direction of arrowsfrom the line Il-II of FIG. I; and

FIG. 3 is an end elevational view as seen in the direction of arrow IIIin FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, there isshown a portion of a cinematographic apparatus, such as a motion picturefilm projector, which comprises a housing H supporting a spindle l for areel '2 containing a supply of convoluted motion picture film 3. The

leader (i.e., the free end portion)of the outermost convolution of thefilm 3 is shown at 24. The reel 2 is surrounded by a magazine orcassette 4 whose lower end is open, as at 5, to permit entry of a drivewhich serves to rotate the reel 2 in a direction to pay out the film.The drive comprises an endless belt 6 which is trained over pulleys 7, 8and 9 mounted on a triangular plate-like carrier 12 pivotable about theaxis of the shaft 10 for the pulley 9. This pulley is driven by anelectric motor 11 mounted in the housing H. When the motor 11 is on, thebelt 6 travels in a counterclockwise direction and the reel 2 rotates ina clockwise direction (both directions are indicated by arrows) when thecarrier 12 is pivoted to the operative position shown in FIG. 1. Suchpivoting is effected by a lever 13 which is mounted on a pivot pin 14 ofthe housing H and the free arm of which supports the carrier 12 frombelow. The means for pivoting the lever 13 in a clockwise direction tothe position shown in FIG. 1 includes a prime mover 15, preferably areversible electric motor, having an output shaft 16 which drives a gearsegment 18 on the upper end of the lever 13 by way of a transmissionschematically indicated by the phantom line 17. This transmissionincludes a pinion which meshes with the gear segment 18 and a frictionclutch (not specifically shown) which becomes operative when the lever13 reaches the illustrated position. Thus, the motor 15 can continue tooperate after the belt 6 moves into engagefor the leader (the leaderadvancing along such path moves ment with the outermost convolution ofthe film 3. Since the motor is reversible, it can pivot the lever 13 ineither direction.

The automatic film threading mechanism of the motion picture projectorfurther comprises deflector means which serves to direct the leader 24of the film 3 into a path 27 defined by two guides 28, 29 which aremounted in the housing H. Once the leader 24 enters into and advancesalong the path 27, the perforations of the film 3 are engaged by asuitable film transporting mechanism, for example, a mechanism includinga customary claw pull-down 41, which thereupon continues to transportthe film along the predetermined path so that the leader can beautomatically connected to the core of a takeup reel, not shown. Thedeflector means includes a slide-like film engaging element 23 whoseblade or wedge-like tip 25 can be moved into engagement with theoutermost convolution of the film 3 slightly downstream of the point ofengagement between the film 3 and the belt 6. The film directing surface26 of the slide 23 then causes the leader 24 to travel along suchsurface and to automatically enter the path 27 defined by the stationaryguides 28 and 29. The slide 23 is fonned with an elongated slot 30 fortwo fixedly mounted guide pins or posts 31, 32 which confine the slideto movement along a straight path as indicated by the phantom line 33.This path extends at least substantially radially of the reel 2. Thedisplacing means for moving the slide 23 up or down along the posts 31,32 includes the aforementioned motor 15, its output shaft 16 and atransmission which is indicated by a phantom line 19. This transmissionincludes a straight toothed rack 22 which is preferably recessed intothe film directing surface 26 of the slide, a pinion 21 which mesheswith the rack 22 and is mounted on a shaft 20, and a friction clutchwhich is shown in FIGS. 2 and 3. The friction clutch is interposedbetween the shaft and the pinion 21 so that, when the tip of the slide23 engages with and is arrested by the outermost convolution of film 3on the reel 2, the motor 15 can continue to operate but the pinion 21 isthen at a standstill. An advantage of the illustrated rack 22 is that itcannot interfere with the movement of leader 24 along the film directingsurface 26 so that the leader can readily enter the path 27 defined bythe guides 28, 29 when the motor 1] drives the belt 6 and the motor 15maintains the belt in engagement with the outermost convolution of thefilm. The pinion 21 is mounted at a level below the guide 28 whichcrosses the film directing surface 26. The uppermost portion of the path27 is straight and extends along the right-hand side of the guide 28;this guide forms with the guide 29 a narrow channel in which the leader24 travels toward the claw pull-down 41. The path 27 makes an obliqueangle with the path 33.

An important advantage of the reciprocable film engaging slide 23 isthat the oblique angle between the surface 26 and the right-hand surfaceof the guide 28 (path 27) remains unchanged in each position of theslide. Also, the angle of deflection of the leader 24 from the circularpath around the spindle 1 into the path along the surface 26 is alsoconstant, irrespective of the diameter of the fully convoluted film 3.The extent of straight-line movement of the slide 23 along the path 33(radially of the reel 2) at least equals but can exceed half thedifierence between the diameter of the longest film and the diameter ofthe shortest film which is intended to be stored on a reel 2. Otherwisestated, the extent of straight-line movement of the slide 23 radially ofthe shaft 1 at least equals the difference between the radii of thelongest and shortest films which are to be viewed in the improvedprojector. The slide 23 constitutes a very simple but highly reliableand efficient film engaging and directing element which is superior topresently known film directing levers. Such levers are pivotable intoengagement with the outermost convolution of the film so that the angleof deflection of the leader from the next-to-the-outermost convolutionvaries whenever the reel which stores a certain length of convolutedfilm is replaced with a reel storing a longer or shorter film. Moreover,the angle of deflection of the leader from travel along a pivotablelever to travel in a channel between stationary guides also varies as afunction of the length of convoluted film. All this is avoided by thesimple expedient of utilizing a slide-like film engaging and directingelement which reciprocates radially or substantially radially of thereel.

The aforementioned friction clutch of the transmission 19 is shown inFIGS. 2 and 3. The clutch comprises a disk 35 which is fixed to androtates with the shaft 20 when the motor 15 is i on, a disk-shapedpressing member 35a which biases the pinion 21 against the disk 35, atwo-armed leaf spring 34 which biases the pressing member 35a againstthe adjacent surface of the pinion 21, a split ring 36 or a likeretainer for the spring 34, and two pairs of pins 37, 38 and 39, 40 eachpair of which flanks one arm of the spring 34. The pins 37-40 aremounted on the pressing member 35a. The pinion 21 is rotatably mountedon the shaft 20 between the disc 35 and the pressing member 35a.

The operation:

When the projector is idle, the lever 13 permits the carrier 12 todescend so that the belt 6 is disengaged from the outermost convolutionof the film 3 on the reel 2. The pinion 21 of the transmission 19maintains the slide 23 in its lower end position in which the post 32engages the surface at the upper end of the slot 30 and the tip 25 isremote from the outermost convolution of the film. In order to start thefilm threading operation, the user of the projector completes thecircuit of the motor 15 so that the motor rotates in a direction topivot the lever 13 in a clockwise direction by way of the transmission17 whereby the lever 13 assumes the position shown in FIG. 1 and urgesthe belt 6 against the outermost convolution of the film 3. Theaforementioned (non-illustrated) friction clutch in the transmission 17permits the motor 15 to drive the output shaft 16 while the belt 6 bearsagainst the film. The output shaft 16 of the motor 15 simultaneouslydrives the transmission 19 whereby the friction clutch of FIGS. 2 and 3rotates the pinion 21 in a direction to move the rack 22 and the slide23 upwardly until the tip 25 engages the outermost convolutionimmediately orclosely downstream of the point where the outermostconvolution is engaged by the belt 6.

In the next step, the user starts the motor 11 which drives the belt 6in a counterclockwise direction so that the reel 2 rotates clockwise andmoves the leader 24 against the surface 26 of the tip 25 not later thanafter the reel 2 completes a full revolution. The thus deflected leader24 slides along the surface 26 and is automatically intercepted by theright-hand surface of the guide 28 which directs the leader into thepath 27. The advancing leader 24 is thereupon engaged by the claw of thepull-down 41 and is automatically transported past the gate (not shown)and on toward the core of the takeup reel. A portion of the path 27extends along the periphery of the pinion 21; however, such film cannotbe damaged by the teeth of the pinion 21 because the latter is flankedby the disk 35 and pressing plate 35a(see particularly FIG. 2). Thepinion 21 comes to a standstill as soon as the tip 25 engages the film 3but the motor 15 can continue to drive the shaft 16 because the spring34 permits the disk 35 to rotate with the shaft 20 relative to thepinion 21. The direction of rotation of the motor 15 can be reversed assoon as the leader 24 reaches the pull-down 41. This causes the tip 25of the slide 23 to descend and the lever 13 is pivoted in acounterclockwise direction to permit the carrier 12 to move the belt 6away from the film. The motor 11 is thereupon arrested. The means forreversing the direction of rotation of the motor 15 forms no part of theWithout further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featureswhich fairly constitute essential characteristics of the generic andspecific aspects of my contribution to the art and, therefore, suchadaptations should and are intended to be comprehended within themeaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

I claim:

1. In a cinematographic apparatus, a combination comprising a housing; areel rotatably mounted on said housing and supporting a supply ofconvoluted film whose leader constitutes the free end portion of theoutermost convolution, the diameter of said outermost convolution beingone of a predetermined range of diameters including a maximum and aminimum diameter; and a film threading mechanism, comprising guide meansdefining a first path for the leader, drive means for rotating the reelin a direction to pay out the film, and deflector means for directingthe leader into said first path including a film engaging elementmovable toward and away from the outermost convolution of the film alonga second path having an at least substantially straight portion alongwhich said element moves during travel toward actual engagement with theoutermost convolution, the length of said straight portion of saidsecond path being at least equal to half the difference between saidmaximum and minimum diameters, and displacing means for moving saidelement along said second path, the orientation of said straight portionof said second path remaining substantially constant during the movementof said element irregardless of the diameter of the outermostconvolution of film, whereby said element deflects the leader into saidfirst path when it engages the outermost convolution of the film whilethe reel rotates in said direction.

2. A combination as defined in claim 1, wherein the straight portion ofsaid second path extends at least substantially radially ofsaid reel.

3. A combination as defined in claim 1, wherein said first path has aportion which makes an obtuse angle with the straight portion of saidsecond path.

4. A combination as defined in claim 1, wherein said drive meanscomprises an endless belt which is movable into and from engagement withthe outermost convolution of film on said reel.

5. In a cinematographic apparatus, a combination comprising a housing; areel rotatably mounted on said housing and supporting a supply ofconvoluted film whose leader constitutes the free end portion of theoutermost convolution; and a film threading mechanism, comprising guidemeans defining a first path for the leader, drive means for rotating thereel in a direction to pay out the film, and deflector means fordirecting the leader into said first path including a film engagingelement movable toward and away from the outermost convolution of thefilm along a second path having an at least substantially straightportion and displacing means for moving said element along said secondpath whereby said element deflects the leader into said first path whenit engages the outermost convolution of the film while the reel rotatesin said direction,

said displacing means comprising a rack-and-pinion drive.

6. A combination as defined in claim 5, wherein said rackand-piniondrive comprises a rack rigid with said film engaging element and adriven pinion meshing with said rack.

7. In a cinematographic apparatus, a combination comprising a housing; areel rotatably mounted on said housing and supporting a supply ofconvoluted film whose leader constitutes the free end portion of theoutermost convolution; and a film threading mechanism, comprising guidemeans defining a first path for the leader, drive means for rotating thereel in a direction to pay out the film, and deflector means fordirecting the leader into said first path including a film engagingelement movable toward and away from the outermost convolution of thefilm along a second path having an-at least substantially straightportion and displacing means for moving said element along said secondpath whereby said element deflects the leader into said first path whenit engages the outermost convolution of the film while the reel rotatesin said direction, said displacing means comprising prime mover meansand a transmission connecting said prime mover means with said filmengaging element, said transmission including a friction clutch whichpermits said element to come to a standstill in response to engagementwith the film while said prime mover means continues to drive saidtransmission means.

8. In a cinematographic apparatus, a combination comprising a housing; areel rotatably mounted on said housing and supporting a supply ofconvoluted film whose leader constitutes the free end portion of theoutermost convolution; and a film threading mechanism, comprising guidemeans defining a first path for the leader, drive means for rotating thereel in a direction to pay out the film, and deflector means fordirecting the leader into said first path including a film engagingelement movable toward and away from the outermost convolution of thefilm along a second path having an at least substantially straightportion and displacing means for moving said element along said secondpath whereby said element deflects the leader into said first path whenit engages the outermost convolution of the film while the reel rotatesin said direction, said element having a film directing surface whichdirects the leader into said first path and said displacing meanscomprising a driven pinion and a rack meshing with said pinion, saidrack being recessed into said film directing surface of said element.

9. In a cinematographic apparatus, a combination comprising a housing; areel rotatably mounted on said housing and supporting a supply ofconvoluted film whose leader constitutes the free end portion of theoutermost convolution; and a film threading mechanism, comprising guidemeans defining a first path for the leader, drive means for rotating thereel in a direction to pay out the film, and deflector means fordirecting the leader into said first path including a film engagingelement movable toward and away from the outermost convolution of thefilm along a second path having an at least substantially straightportion and displacing means for moving said element along said secondpath whereby said element deflects the leader into said first path whenit engages the outermost convolution of the film while the reel rotatesin said direction, said displacing means comprising a portion alongwhich the leader advances in said first path.

1. In a cinematographic apparatus, a combination comprising a housing; areel rotatably mounted on said housing and supporting a supply ofconvoluted film whose leader constitutes the free end portion of theoutermost convolution, the diameter of said outermost convolution beingone of a predetermined range of diameters including a maximum and aminimum diameter; and a film threading mechanism, comprising guide meansdefining a first path for the leader, drive means for rotating the reelin a direction to pay out the film, and deflector means for directingthe leader into said first path including a film engaging elementmovable toward and away from the outermost convolution of the film alonga second path having an at least substantially straight portion alongwhich said element moves during travel toward actual engagement with theoutermost convolution, the length of said straight portion of saidsecond path being at least equal to half the difference between saidmaximum and minimum diameters, and displacing means for moving saidelement along said second path, the orientation of said straight portionof said second path remaining substantially constant during the movementof said element irregardless of the diameter of the outermostconvolution of film, whereby said element deflects the leader into saidfirst path when it engages the outermost convolution of the film whilethe reel rotates in said direction.
 2. A combination as defined in claim1, wherein the straight portion of said second path extends at leastsubstantially radially of said rEel.
 3. A combination as defined inclaim 1, wherein said first path has a portion which makes an obtuseangle with the straight portion of said second path.
 4. A combination asdefined in claim 1, wherein said drive means comprises an endless beltwhich is movable into and from engagement with the outermost convolutionof film on said reel.
 5. In a cinematographic apparatus, a combinationcomprising a housing; a reel rotatably mounted on said housing andsupporting a supply of convoluted film whose leader constitutes the freeend portion of the outermost convolution; and a film threadingmechanism, comprising guide means defining a first path for the leader,drive means for rotating the reel in a direction to pay out the film,and deflector means for directing the leader into said first pathincluding a film engaging element movable toward and away from theoutermost convolution of the film along a second path having an at leastsubstantially straight portion and displacing means for moving saidelement along said second path whereby said element deflects the leaderinto said first path when it engages the outermost convolution of thefilm while the reel rotates in said direction, said displacing meanscomprising a rack-and-pinion drive.
 6. A combination as defined in claim5, wherein said rack-and-pinion drive comprises a rack rigid with saidfilm engaging element and a driven pinion meshing with said rack.
 7. Ina cinematographic apparatus, a combination comprising a housing; a reelrotatably mounted on said housing and supporting a supply of convolutedfilm whose leader constitutes the free end portion of the outermostconvolution; and a film threading mechanism, comprising guide meansdefining a first path for the leader, drive means for rotating the reelin a direction to pay out the film, and deflector means for directingthe leader into said first path including a film engaging elementmovable toward and away from the outermost convolution of the film alonga second path having an at least substantially straight portion anddisplacing means for moving said element along said second path wherebysaid element deflects the leader into said first path when it engagesthe outermost convolution of the film while the reel rotates in saiddirection, said displacing means comprising prime mover means and atransmission connecting said prime mover means with said film engagingelement, said transmission including a friction clutch which permitssaid element to come to a standstill in response to engagement with thefilm while said prime mover means continues to drive said transmissionmeans.
 8. In a cinematographic apparatus, a combination comprising ahousing; a reel rotatably mounted on said housing and supporting asupply of convoluted film whose leader constitutes the free end portionof the outermost convolution; and a film threading mechanism, comprisingguide means defining a first path for the leader, drive means forrotating the reel in a direction to pay out the film, and deflectormeans for directing the leader into said first path including a filmengaging element movable toward and away from the outermost convolutionof the film along a second path having an at least substantiallystraight portion and displacing means for moving said element along saidsecond path whereby said element deflects the leader into said firstpath when it engages the outermost convolution of the film while thereel rotates in said direction, said element having a film directingsurface which directs the leader into said first path and saiddisplacing means comprising a driven pinion and a rack meshing with saidpinion, said rack being recessed into said film directing surface ofsaid element.
 9. In a cinematographic apparatus, a combinationcomprising a housing; a reel rotatably mounted on said housing andsupporting a supply of convoluted film whose leader constitutes the freeend portion of the outermost convolution; and a film threadingmechanism, comprisiNg guide means defining a first path for the leader,drive means for rotating the reel in a direction to pay out the film,and deflector means for directing the leader into said first pathincluding a film engaging element movable toward and away from theoutermost convolution of the film along a second path having an at leastsubstantially straight portion and displacing means for moving saidelement along said second path whereby said element deflects the leaderinto said first path when it engages the outermost convolution of thefilm while the reel rotates in said direction, said displacing meanscomprising a portion along which the leader advances in said first path.